扬麦16抗赤霉病位点QFhb-yaas-3BL的精确定位与育种效应分析

Fusarium Head Blight (FHB) has devastatingly damaged wheat production and thus the food security. Breeding durable resistant cultivars are the most effective measures for the management and control of the disease. Sumai 3 as the most resistant source could not be applied in breeding on account of its poor agronomic characters. Yangmai 16 has been the predominant variety in the Yangtze River region, which have moderate resistance to FHB. Our previous experiments indicated that the source of FHB resistance of Yangmai16 is different from Sumai3. Combing 660K SNP genotyping and phenoyping of type 2 resistance in the field environments, a novel QTL of major effect on FHB resistance, designated as QFhb-yaas-3BL, was identified in a DH population derived from the cross of cv. Zhongmai 895 × cv.Yangmai16", and this QTL is donored by cv.Yanmgai4 based on pedigree and haplotype analysis. In this proposal, we are going to (1) fine mapping the major QTL locus QFhb-yaas-3BL using an introgression lines secondary mapping population of Yangmai 4, the FHB resistant donor of Yangmai 16, backrossded into highly susceptible cultivar Yanzhan 1; (2) to identify the candidate region of QFhb-yaas-3BL and develop tightly linked molecular markers; (3) to estimate the genetic effects and breeding values of QFhb-yaas-3BL on FHB resistance and yield traits in near-isogenic lines (NIL) segregating in the target locus; (4) to investigate the distribution of the favorable and unfavorable alleles in a wheat collection of commercial culivars released in recent years. The results will provide novel resources and powerful markers for improving FHB resistance in breeding programs.

赤霉病严重危害小麦生产和粮食安全，培育稳定的抗病品种是防控赤霉病最有效措施。但被广泛认可的抗源苏麦3号（携带主效抗病基因Fhb1），农艺性状较差，不利于育种应用。申请者课题组培育的扬麦16是长江中下游麦区的主导品种，具有稳定的赤霉病抗性和丰产性，且不携带Fhb1。我们前期利用“中麦895×扬麦16”DH群体结合660K SNP基因型和田间赤霉病抗扩展鉴定，定位到扬麦16中一个新的抗赤稳定位点QFhb-yaas-3BL，系谱和目标位点单倍型分析表明该抗性位点来自扬麦4号。本研究重点（1）利用扬麦4号为供体的染色体片段导入系，构建次级分离群体对QFhb-yaas-3BL进行精确定位；（2）进行候选基因预测，开发紧密连锁分子标记；（3）利用近等基因系评鉴该位点抗赤遗传效应和对产量等性状的影响；（4）利用自然群体研究该位点等位变异在现有品种中的分布，明确其育种利用价值。

小麦赤霉病（Fusarium head blight）是由亚洲镰刀菌（Fusarium asiaticum）和禾谷镰刀菌（Fusarium graminearium）等病原菌引起的一种世界性病害，危害我国长江流域乃至全国小麦安全生产的最主要病害。培育和种植抗病品种是控制小麦赤霉病的最有效途径。目前生产上可供利用的赤霉病抗源和抗病基因稀少，国内外公认的苏麦3号、望水白等综合农艺性状差，很难被利用。项目组所在单位育成的小麦品种扬麦16是长江中下游麦区主导品种，赤霉病抗性稳定，其中的抗病基因/QTL尚不清楚。与传统赤霉病抗源抗性与农艺性状可能存在连锁累赘相比，扬麦16综合农艺性状优良，推测其赤霉病抗性基因与产量之间没有不利连锁，在小麦抗赤霉病遗传改良中更易于利用。本项目研究结果如下：（1）利用携有目标区段的导入系，构建了次级分离群体，精细定位了扬麦16的抗赤霉病位点QFhb-yaas-3BL，将目标区间缩小至250Mb以内。（2）在精细定位区间挖掘了在抗感混池和亲本之间有显著差异的基因，明确QFhb-yaas-3BL的候选基因3个。开发了可用于育种的分子标记KASP-3BL。（3）在近等基因系里发现其抗病等位变异可以降低赤霉病严重度35.21%，提高小区产量20.23%。（4）明确了QFhb-yaas-3BL抗病等位变异在长江中下游品种中占比56.89%，其抗病等位变异可降低赤霉病严重度20.78%，提高小区产量19.63%，与Fhb1抗病等位变异聚合可以降低赤霉病严重度48.44%，提高小区产量15.67%，具有很好的育种利用价值。本项目研发出抗赤霉病高产育种的新技术1套，创制出抗病性好、农艺性状优良的品系扬M465，产量比对照高3.23%，为解决抗赤霉病与高产相结合的世界性难题奠定了基础。在本项目的资助下，发表SCI论文2篇（第一标注），中文核心期刊论文2篇（第一标注和第三标注），申请并授权专利2项。